The Dow is just the oldest index so that is the only reason it is still around really.
It is a price weighted index of just 30 stocks.
The S&P 500 is a market weighted index of 500 stocks.
Thus a truer picture of the market IMO
BTW the Obama S&P 500 returned 2.5 times as much as Trump's S&P 500 for the same number of days in office.
If you look at the S&P 400 midcap, and S&P 600 smallcap the differences are way more pronounced.